Method of making structural elements of sheet metal



' June 10, 1941. V o. OECKL ETAL 2,244,847

METHOD OF MAKING STRUCTURAL ELEMENTS OF SHEET METAL Filed Sept.- 15, 1938 2 Sheets-Sheet 1 In ve n tom. Orro 0501 [ML MLLA Nfl 441,61 5

mmv y June 10, 1941. K o. OECKL EI'AL 2,244,847

METHOD Of MAKING STRUCTURAL; ELEMENTS OF SHEET METAL Filed Sept. 15, 1938 Sfieets-Sheet 2 I Inventors:

Patented June 10, 1941 METHOD OF rummasrauc'ruaan murmurs or snna'r mama one Oeckl, Berlln-Schoneb erg, and Emil Kolla-nd, Berlin-Jo to Henschel Flune c'werke 'Kreis Teltcw, Germany 'Aii'lllication September 15, 193a, Serial No. 230,096 ,In Germany December 27, 1937 v 2 Claims. (01. ea -155) The present invention relates to sheet'metalelements of structures such as airplane bodies and wings, car bodies, truss works etc., in short of structures combining light weight with great strength. Such elements are generally produced by pressing, drawing, or similar operations wherein each individual pattern hitherto required its owntools or dies. Wherever, as for instance in the wing structure of an airplane,

' gradually tapering forms occur, a single structure made it necessary to provide for a great number of different tools corresponding to the various dimensions of even similarly shaped elements. Particularly in cases where airplane structures are to be made in'a small number rather than in mass production, e. g. in developing a new type, the relation of cost and labpr spent on tools to the number of structures produced with their aid is therefore very dissatisfying.

The present invention aims to overcome this drawback, and it is one of its objects to provide a means and a method whereby the cost and labor invested in the tools for a structure and the number of individual tools can be considerably lowered.

A further object of the invention is the provision of a means and a method whereby the labor in producing the individual elements of a structure and the occurring waste, can be reduced.

According to the invention these objects will be attained by so designing the individual elements of a set of similar elements of a structure that a first edgeof each element is shaped according to the requirements or outlines of the desired structure, and that a'second edge of each element has the same shape as the first edge of another element. This being done, a metal sheet may be shaped by suitable means and methods into a preliminary product or body which comprises a plurality of such elements adjacent and immediately connected to each other. By severing the so prepared body along the lines each two elements have in common, the individual elements will be obtained with a minimum of labor, waste, and number of dies.

} Further objects and details of the invention will be apparent from the description hereinafter and the accompanying drawings showing several embodiments thereof by way of example.

In the drawings: Fig. 1 Ba top plan view of an embodiment of the invention comprisingv a plurality of ele-' ments.

Germany, 'asslgnors A. G., Schonefeld,

Fig. 2 is a perspective cross-section along line 22 in Fig, l, onan enlarged scale.

Fig.'2a is a perspective view of one of the elements of Fig. 1.

Figs. 3 to 5 are top plan viewed-three different embodiments.

Fig. 6 ma perspective cross-section along line 6-8 of Fig. 5,.on an enlarged scale. e

Fig. 7 is a top plan view or a structure in which elements of the embodiments of Figs. 2 and 5 are used.

Figs. 8 and 9 are a side elevation and a top view respectively of another embodiment.

Fig. 10 is a diagrammatic cross-section of .a

set of dies for making the body of Figs. 8 and 9,

and

Fig. 11 is a perspective view of a male die for a diflerently shaped bodywhich is also visible in the figure.

In Fig. 1, body I is an intermediate product which comprises three elements 2', 2", and !"f of similar shape. Body I consists of a metal sheet provided with corrugations which are pressed with the aid of conventional means or produced in any suitable manner of operation. In the instant case, the longitudinal axis of each corrugation is a line having two bends at 3 and l,

and the cross-section (see Fig'. 2) shows channels which are open alternately towards the top and the bottom. By severing the body i along the lines a and ,aifollowing the longitudinal extension-oi the corrugations, three individual elements 2', 2", and 2' can be obtained, each element having a substantially Z-shaped crosssection. It will be noticed that these elements are very similar to eachother in. shape, they 'diiIer, however, as to the radii of their respective bends as clearly apparent in Fig. 1. Nevertheless, the present invention permits. forming of the three elements by means oi. a single die or a single set of dies comprising a male and a female part, provided such die or set of dies is suitably formed to produce the complete body I. In order to make this possible it is necessary that a first edge of each of the elements 2',

' the elements 2', 2 and 2"" which are for instance reinforcing struts ofan airplane part, have left hand edges corresponding to the form 01' the air plane while the right-hand edge of element 2' is made congruent with the left band edge oi element 2", and the right-hand edge of element 2" is congruent with the left-hand edge of element 2". Although I have shown only three elements in Fig. 1, it will be understood that any desired number of elements within the capacity of the pressing machine may be combined into one body I. I

It will be apparent that by first making an intermediate product like body I and, thereafter, dividing it by a cutting operation into individual elements, labor, material and tools will be saved in comparison to the conventional manner of using a separate tool or set of tools for each element.

Figs. 3 and 4 show bodies 6 and 8 respectively comprising elements I, 'I" and 9', 9", 9 respectively. The arcuate elements-1', 1", formed to constitute rib flanges of an airplane wing, are preferably arranged one within the other and symmetrically with respect to a center line bb. Element 1' is designed as an inner rib flange located near the airplane body, while the smaller element 1" may be used as an outer rib flange, that is to say, nearer the wing tip.

In a similar manner, the elements 9', 9", 5'", constituting transverse members of an airplane body are arranged substantially concentric with respect to each other. The elements of Figs. 3 and 4 have cross-sections similar to those of the elements of Fig. 2.

A different cross-section of elements is shown in Fig. 6 by way of example. This cross-section is destined for use as reinforcing members H" and H' of airplane wings. The intermediate product of body III for these elements is illustrated in Fig.5 and the lines along which the body is to be divided are indicated with I. It is to be understood that the individual elements of Figs. 3 to 5 are to be designed according to the same principle and prescription given with respect to the elements 2', 2" and 2' of Figs. 1 and 2. T

The application of the elements thus obtained is illustrated in Fig. 7 showing a portion of a wing rib I21 The rib comprises a rib flange l' of Fig. 3, and the reinforcing elements lil' and H" of Fig. 5. The elements may be connected to each other by suitable means, for instance by riveting .or welding.

In the foregoing, we have described the combination of elements in preliminary products which extend substantially in one plane. In

many cases where the particular crosssection' permits it, we prefer to arrange the elements so that an intermediate product or body isiiormed which has convergent flanks or which is tapered from all sides or at least a portion thereof.

A body I3 of this kind is illustrated in Figs. 8 and 9 by way of example. Body I: comprises the elements ll. l4", ll', each having a Z- shaped cross-section slightly differing from that of Fig. 2. As to the longitudinal direction, however, the corrugations of Fig. 8 are similarly shaped to those of Fig. 2. The individual elements l4',-l4", M may be obtained by dividing body I3 along the lines J5 to It. The arrangement of the elements in an intermediate product such as that of Fig. 8 which may be denoted as a roof-shaped body with cascade-like flanks offers the advantage that the pressing operation can be facilitated, and that the forming of the body can be accomplished from the succession, whereby the occurrence of folds can be avoided. Furthermore, the severing of the body into individual elements will be facilitated because the lines of the cuts are readily awessible owing to the roof-shaped form. For this reason, it is advisable to design the individual elements so that those edges of an element which conform with the respective edges of the adja cent elements are located in difierent planes whereby an intermediate product of roof-shaped structure with cascade-like flanks can be obtained.

In order to press a body free of folds, as stated hereinbefore, we prefer to use a set of dies which will be described hereinafter with reference to Fig. 10. In this figure, the set of dies comprises a male die 20 and a female die 2|. Die 20 is made of a suitable rigid material and is of the conventional type, that is to say, its outer surface corresponds to the inner surface of the body to be pressed, in the instant case, of a bodv' according to that of Figs. 8 and 9. .The female die 2|, however, has a particular novel structure. According to the invention, it comprises a hollow or pot-shaped body 23 of a rigid material, which is filled with a resilient substance, such as soft rubber plates 24. A pressing force may be applied from the top upon the body 23 in the direction of the arrow 25. For this purpose, a hydraulic plunger 26 may be provided. If now female die 2| is lowered upon a metal sheet 21 placed on top of die 20, the pressing power will bend the metal into the steps or recesses thereof.

The pressure, however, will not be uniform top of die 20 with the center portion of the sheet thereupon enter. into the resilient sub- -stance 24. In consequence thereof, the latter will be compressed more strongly in its center than in its outer portions, and as a further consequence thereof, the job i. e. the sheet metal body sheet. Thus, the occurrence of folds will be prevented. It goes without saying that the female die described may also be used advantageously in pressing. other bodies which are not roofshaped or tapered, as for instance in the production of bodies according to Figs. 1 to 6.

Fig. 11 fllustrates another male die 3|] with an intermediate product 3| shaped with its aid. The elements obtainable from body if are curved similarly to those oi Fig.- 3, and have a simple angular cross-section if the cuts are taken along the corners of the recesses at 32. The die shows clearly the cascade-shaped convergent flanks. In order to press the body 30, a female die may beusedsuchas2|ofFlg.10.

With respect to the lower surface 29 of the die 2|,wewishtostatethatitisnotnecessarytoform that surface plane as shown in Fig. 10. The active surface of the female die may have any suitable curvature or outline provided that in applying the die the center portion of the resilient substance will be compressed more than its outer portions.

Elements having other and even more shapes and cross-sections may be made according to'the principle of the present invention and it will be apparent to those skilled in the art that it is possible to adapt the shape of the individual elements to the most various purposes. The lines of division of the intermediate bodies may be middle portion towards the outside in g adual taken 310118 the edges of such intermediate body,

or through its plane surfaces, either perpendicular or parallel to the direction of It is even not absolutely necessary to combine into an intermediate product elements which are entirely similar to each other. Thus, the parts of an airplane body for instance, may be combined with elemmts of an airplane win: into a common intermediate product. It is possible that in such a case a certain small waste will occur. 'lhis, however, will be insignificant in tion oi the labor and number of dies saved in each instance.

Although we have described in the foregoing specification and in the appended claims partsof an airplane structure by way 0! example, we wish it to be understood that the application of our invention is possible with equal or similar advantase to many other structures as for instance structures of car bodies, ribs and other members of vehicles, and so on.

We claim:

1. The method of making a series of similarly shaped structural elements adapted to occupy spaced pontions in a constructional assembly, comprising the steps of forming the individual elementsoisaidseriesasastructuralmembergs larser element, by eon-nesting a piece of sheet so metalsoastoincludetheangularlyrela faces oi'allsaidelementsconnectedwith other along their congruent contours respectively, and eachpartoieachelementbeinzspacedtrmnthe copartoithesdlaemtelementbya' semblylncludinzanouteri'rameotvaryingmner dimensions andmnerbracingelemmhmvlnldimensions totheinnerdimensions of the irame m m g torminstheoutertrsmetormhmamm m i ansmarlyrelatedmessimuartoesen rsllFlill otherinshapebut diileringmsisesothatthe' mtercontmiroiasmallerelementknbshntiallyconzruenttotheinneroontourolalarterdement, separating the similarly shaped portions by cutting the blank along spaced parallel lines whicharelocatedinpnsltionsm adiacentportionaandpositioninceaehotsneh portionsintheinzly part oi saidtrame. r 7

v ormomrm mm. KOLLARD. 

